QSX15 Cummins Cylinder Block 4309390/5473345 Parts Catalog Ref No. Part Name Part No. Required 　 Cylinder Block BB1928-01 　 1 Cylinder Block Stiffener 3680425 1 2 Hexagon Flange Head Cap Screw 3680781 10 　 Threaded Plug 3678610 1 3 Threaded Plug 3678602 1 4 O-Ring Seal 3678603 1 　 Threaded Plug 3678921 3 5 Threaded Plug 3678922 1 6 O-Ring …